This invention relates to a new apparatus and method of determining the location of the meniscus at the interface of two immiscible fluids and the determination of the relative lengths of the two fluids such as formed by either liquid-to-gas or liquid-to-liquid within the tube.
This invention has utility in conjunction with a sight tube and, particularly, a U-tube inclined manometer for electronically determining differential pressures and may detect differences as low as 0.001 inches water column imposed on the manometer. This invention also has utility for photoelectronic determination of the height of a liquid column within a sightglass as commonly found on boilers or liquid vessels.